NASA's Transition Region and Coronal Explorer (TRACE) spacecraft recorded a
bright but extremely short-lived explosion in the atmosphere of the Sun. The
explosion, called a flare, was observed on May 31, 1998 in extreme
ultraviolet light using the telescope on board TRACE.

"TRACE is demonstrating that large scale events can happen very rapidly on
the Sun," said Dr. Alan Title, the TRACE Principal Investigator from the
Stanford Lockheed Institute for Scientific Research (SLISR) in Palo Alto,
Calif. "Although less than 200 miles wide, the flare was about 55,000 miles
long. It appeared and vanished in just a few minutes. TRACE was able to
detect this explosion because it can maintain high cadence, high resolution
imagings for long durations. At the time of the explosion, TRACE was taking
images at a cadence of a frame every 86 seconds and an exposure time of 28
seconds."

High resolution movies of this explosion will be presented at a press
conference Monday, June 8, 1998 at 2:30 A.M. PDT during the spring meeting
of the American Astronomical Society in San Diego, Calif.

"TRACE is operated in conjunction with the ESA/NASA Solar and Heliospheric
Observatory (SOHO) spacecraft. The Michelson Doppler Imager (MDI) on SOHO
was producing magnetic and velocity maps at the time. These tell us where
the flare occurred with respect to the Sun's magnetic field, and further
analysis may reveal evidence for Sun quakes. The SOHO Extreme-Ultraviolet
Imaging Telescope (EIT) was taking full disk images during the same interval
at a 17 minute cadence. About an hour before the flare, the EIT movie shows
that a coronal mass ejection (eruption of hot gas from the Sun, abbreviated
CME) occurred on the edge of the Sun. It is well known that such events
trigger waves that can travel across the entire Sun. It may be that the
trigger for the flare came from the blast wave associated with the CME. We
are now studying the EIT data and will be on the look out for similar
events in future data," said Title.

"The TRACE spacecraft had been following an active region's (NOAA 8227)
passage across the solar disk since May 26, 1998. Suddenly, at 3:56:18 UTC
on May 31, the region brightened in an area that was approximately 'T'
shaped. The top and length of the 'T' were each about 55,000 miles (90,000
km) long and less than 200 miles (350 km) wide. At the same time, the X-ray
detectors on the National Oceanic and Atmospheric Administration's
(NOAA) GOES satellite recorded a doubling of their signals. The explosion is
not visible in the frame taken a couple of minutes earlier at 3:54:52
UTC. This means that the event trigger, if it started from a point, had to
travel at least 55,000 miles in a time period between 58 and 86 seconds
long. This corresponds to a velocity of between 640 and 2,000 miles/second
(2.3 to 7.1 million miles/hour)." said Title.

"The intensity in the exploding region increases by a factor of at least 220
between frames. We don't know exactly how much the increase is because we
don't know when in the exposure the increase occurred. Almost as fast as the
increase is the cooling. A frame 149 seconds later shows almost no evidence
of the event," added Title.

"The TRACE spacecraft is unique in that it has both high spatial and
temporal resolution in the extreme ultraviolet, a wavelength of light that
reveals the multimillion degree Sun. We can image solar activity in finer
detail than existing spacecraft, and we can take a new image once every few
seconds. For example, there are 25 TRACE pixels for each one of SOHO EIT.
Both high temporal and spatial resolution are necessary for our mission,
which is to understand in great detail how energy is transported from the
solar surface into the outer atmosphere. In the past, spacecraft of lower
resolution were forced to average over much larger areas and periods of
time. This made it difficult to get at the fundamental physics," said Title.

The TRACE spacecraft, launched from Vandenberg Air Force Base in Calif.,
Apr. 1, 1998, joins a multinational fleet of International Solar Terrestrial
Physics project spacecraft studying the Sun during a critical period when
solar activity is beginning its rise to a peak early in the new millennium.
The Sun goes through an 11-year cycle from a period of numerous intense
storms and sunspots to a period of relative calm and then back again. The
coming months in the Sun's cycle will provide solar scientists with periods
of intense solar activity interspersed with periods when the Sun is
relatively passive and quiet. This will give TRACE the chance to study the
full range of solar conditions, even in its relatively short planned
lifetime.

TRACE is training it's powerful telescope on the so-called "transition
region" of the Sun's atmosphere, a dynamic region between the relatively
cool surface and lower atmosphere regions of the Sun (about 6,000 degrees
Fahrenheit) and the extremely hot upper atmosphere called the corona (up to
3 million degrees Fahrenheit). Using portions of the telescope sensitive to
extreme-ultraviolet and ultraviolet wavelengths of light, TRACE is studying
the detailed connections between the fine scale surface features and the
overlying, changing atmospheric structures of hot, electrically charged gas
called plasma. The surface features and atmospheric structures are linked by
fine-scale solar magnetic fields. The solar atmosphere is constantly
evolving because the magnetic fields that dominate the corona are continuously
displaced by the convective motions in the outer layers of the Sun just below
the photosphere.

The TRACE science team will also study the evolution of events, such as
massive flarings and huge eruptions, in the Sun's atmosphere. These events
originate at the Sun's visible surface, the photosphere, and travel upward
through it's atmosphere (chromosphere and transition region), and then into
its super-hot corona before speeding out into space, sometimes towards
Earth.

The power of the TRACE telescope to do detailed studies of the solar
atmosphere makes this observatory unique among the current group of
spacecraft studying the Sun. The spacecraft has roughly 10 times the
temporal resolution and 5 times the spatial resolution of previously
launched solar spacecraft. These advances are possible because of the near
Earth "Sun-synchronous" orbit and significant advances in optical coatings
developed at the Lawrence Livermore National Laboratory, Livermore, Calif.,
and an optical system developed at the Smithsonian Astrophysical
Observatory, Cambridge, Mass. A Sun-synchronous orbit is uninterrupted by
Earth's shadow for eight months at a time, allowing the mission the greatest
chance to observe the random processes which lead to flares and massive
eruptions in the Sun's atmosphere.

PHOTO CAPTION:

RAPID SOLAR FLARE IMAGE: This image was taken using the extreme
ultraviolet light telescope on board NASA's Transition Region and Coronal
Explorer (TRACE) spacecraft on May 31, 1998. The bright, roughly "T" shaped
region is a solar flare, an explosion in the Sun's atmosphere caused by the
tearing and reconnection of strong magnetic fields. The top and length of
the 'T' are each about 55,000 miles (90,000 kilometers) long and less than
200 miles (350 kilometers) wide. Although very large, the flare appeared
and vanished in just a few minutes. TRACE was able to detect this explosion
because it can maintain high cadence, high resolution imagings for long
durations. At the time of the explosion, TRACE was taking images at a
cadence of a frame every 86 seconds and an exposure time of 28 seconds.

SPACECRAFT IMAGES CAPTURE MAGNETIC ENERGY BURST ON SUN

The first images from NASA's Transition Region and Coronal
Explorer (TRACE) spacecraft reveal activity in the solar
atmosphere in stunning detail and include the first detailed
observations of a magnetic energy release, called a magnetic
reconnection.

The magnetic reconnection was observed on May 8, 1998, in a
region of the solar atmosphere where two sets of perpendicular
magnetic loops expanded into each other. Magnetic reconnection
occurs when magnetic fields "snap" to a new, lower energy
configuration, much like when a twisted rubber band unwinds or
breaks. A magnetic reconnection can release vast amounts of
energy and is responsible for explosive events on the Sun, such as
flares, that can cause communication and power system disruptions
on Earth.

High resolution movies of a relatively small but clear
magnetic reconnection event and other spectacular solar activity
observed by TRACE were presented today during the spring meeting
of the American Geophysical Union in Boston.

"The TRACE spacecraft is unique in that it has both high
spatial and temporal resolution in the extreme ultraviolet,
wavelengths of light that reveal the multimillion degree
temperature of the Sun," said Dr. Alan Title, TRACE Principal
Investigator from the Stanford Lockheed Institute for Scientific
Research (SLISR) in Palo Alto, CA. "We can image solar activity
in finer detail than existing spacecraft, and we can take a new
image once every few seconds. Both are necessary for our mission,
which is to understand in great detail how energy is transported
from the solar surface into the outer atmosphere. In the past,
spacecraft of lower resolution were forced to average over much
larger areas and periods of time. This made it difficult to get
at the fundamental physics."

"In our magnetic reconnection movie, we can distinguish the
fine details of the magnetic fields and see how they change during
time periods of about a minute. TRACE has given us many
surprises, and new ones occur nearly every observation. We found
that even large areas of the Sun, some more than 60,000 miles
long, can heat up or cool down significantly and thus appear and
disappear in just a few minutes," said Title.

The TRACE spacecraft, launched from Vandenberg AFB, CA, on
April 1, 1998, joins a multinational fleet of International Solar
Terrestrial Physics project spacecraft studying the Sun during a
critical period when solar activity is beginning its rise to a
peak early in the new millennium. The Sun goes through an 11-year
cycle from a period of numerous intense storms and sunspots to a
period of relative calm and then back again. The coming months in
the Sun's cycle will provide solar scientists with periods of
intense solar activity interspersed with periods when the Sun is
relatively passive and quiet. This will give TRACE the chance to
study the full range of solar conditions, even in its relatively
short planned lifetime.

TRACE is training its powerful telescope on the so-called
"transition region" of the Sun's atmosphere, a dynamic region
between the relatively cool surface and lower atmosphere regions
of the Sun (about 10,000 degrees Fahrenheit) and the extremely hot
upper atmosphere called the corona (up to three million degrees
Fahrenheit). Using portions of the telescope sensitive to
extreme-ultraviolet and ultraviolet wavelengths of light, TRACE is
studying the detailed connections between the fine-scale surface
features and the overlying, changing atmospheric structures of
hot, electrically charged gas called plasma. The surface features
and atmospheric structures are linked by fine-scale solar magnetic
fields. The solar atmosphere is constantly evolving because the
magnetic fields that dominate the corona are continuously
displaced by the convective motions in the outer layers of the Sun
just below the photosphere.

The TRACE science team also will study the evolution of
events, such as massive flarings and huge eruptions, in the Sun's
atmosphere. These events originate at the Sun's visible surface,
the photosphere, and travel upward through its atmosphere
(chromosphere and transition region), and then into its super-hot
corona before speeding out into space, sometimes towards Earth.

The power of the TRACE telescope to do detailed studies of
the solar atmosphere makes this observatory unique among the
current group of spacecraft studying the Sun. The spacecraft has
roughly 10 times the temporal resolution and five times the
spatial resolution of previously launched solar spacecraft. A
Sun-synchronous orbit is uninterrupted by EarthÕs shadow for eight
months at a time, allowing the mission the greatest chance to
observe the random processes which lead to flares and massive
eruptions in the Sun's atmosphere.

The TRACE core team consists scientists from Lockheed Martin
Advanced Technology Center, Stanford University, NASAÕs Goddard
Space Flight Center, the University of Chicago, Montana State
University, and the Harvard-Smithsonian Center for Astrophysics.
Images to support this story are available at:

National Aeronautics and Space Administration
John F. Kennedy Space Center

March 24, 1998

TRACE SPACECRAFT TO BE LAUNCHED ABOARD PEGASUS XL APRIL 1

The launch of NASA's Transition Region and Coronal Explorer (TRACE)
spacecraft aboard an Orbital Sciences Pegasus XL vehicle is scheduled for
Wednesday, April 1, during a window which extends from 6:38:32 - 6:45:40
p.m. PST. The drop of the Pegasus from the L-1011 aircraft is targeted to
occur inside of the launch window at 6:40 p.m. PST at a location over the
Pacific Ocean approximately 100 miles offshore from Vandenberg Air Force
Base, CA.

The 465-pound TRACE spacecraft will study the evolution of events in
the Sun's atmosphere that originate at the solar surface and travel through
the four regions of the Sun on their way towards Earth. The coming months
in the Sun's cycle will provide solar scientists with periods of intense
solar activity - massive flarings and huge eruptions - interspersed with
periods when the Sun is relatively passive and quiet. Thus, TRACE will be
able to study the full range of solar conditions, even in its relatively
short one-year life.

The prelaunch news conference, to be carried live on NASA Television, is
scheduled to occur on launch day, Wednesday, April 1, at 11 a.m. PST in the
conference room of the NASA-KSC Resident Office at Vandenberg Air Force
Base. Two-way question and answer capability will be available from NASA
Headquarters, Kennedy Space Center and Goddard Space Flight Center.

NASA TELEVISION COVERAGE OF PEGASUS/TRACE

Launch coverage on NASA Television will begin at 5:30 p.m. PST and
continue through spacecraft separation from the Pegasus vehicle. Live
launch commentary and audio of all Pegasus/TRACE briefings will be available
on NASA Television on GE-2, Transponder 9C located at 85 degrees West
longitude.

NASA's Transition Region and Coronal Explorer (TRACE)
mission, scheduled for launch at 9:40 p.m. EST (6:40 p.m. PST)
March 30, 1998, will greatly improve understanding of events in
the Sun's atmosphere, including intense storms and flares,
which can have an impact on power and communications systems on Earth.

The TRACE mission will join a fleet of spacecraft studying
the Sun during a critical period when solar activity is
beginning its rise to a peak early in the new millennium. The
Sun goes through an 11-year cycle from a period of numerous
intense storms and sunspots to a period of relative calm and
then back again. The coming months in the Sun's cycle will
provide solar scientists with periods of strong solar activity
interspersed with periods when the Sun is relatively passive
and quiet. This will give TRACE the chance to study the full
range of solar conditions, even in its relatively short planned lifetime.

TRACE will train its powerful telescope on the dynamic so-
called 'transition region' of the Sun's atmosphere, between the
relatively cool surface and lower atmosphere of the Sun where
temperatures are about 6,000 degrees Fahrenheit, and the
extremely hot upper atmosphere called the corona, where
temperatures are up to 16 million degrees Fahrenheit. Using
instruments sensitive to extreme-ultraviolet and ultraviolet
wavelengths of light, TRACE will study the detailed connections
between the fine-scale surface features and the overlying,
changing atmospheric structures of hot, ionized gas, called
plasma. The surface features and atmospheric structures are
linked by fine-scale solar magnetic fields.

The power of the TRACE telescope to do detailed studies of
the solar atmosphere makes this observatory unique among the
current group of spacecraft studying the Sun.

"The spacecraft has roughly ten times the temporal
resolution and five times the spatial resolution of previously
launched solar spacecraft. Its findings are eagerly awaited by
the solar science community," said Dr. Alan Title, TRACE
principal investigator from the Stanford Lockheed Institute for
Scientific Research in Palo Alto, CA. "We can expect to
resolve some present mysteries of the Sun's atmospheric
dynamics as well as discover new and exciting phenomena."

TRACE will be launched into a polar orbit to enable
virtually continuous observations of the Sun, uninterrupted by
the Earth's shadow for months at a time. This orbit will give
the mission the greatest chance of observing the random
processes which lead to flares and massive eruptions in the
Sun's atmosphere.

The TRACE telescope is really four telescopes in one. Its
30-centimeter (12-inch) primary and six-centimeter (2-inch)
secondary super-polished mirrors are individually coated in
four distinct quadrants to allow light from different
bandwidths (colors) to be reflected and analyzed. An
electronic detector collects images over a 231,000-by-231,000-
mile field of view, nearly 25 percent of the Sun's disk. A
powerful data handling computer enables very flexible use of
the detector array including adaptive target selection, data
compression and image stabilization.

"TRACE was completed on time, under budget, and met all
performance goals," said Jim Watzin, Small Explorer project
manager, NASA Goddard Space Flight Center, Greenbelt, MD. "I'm
really proud of this team. They have produced a magnificent
observatory in a manner that saved NASA nearly $9.7 million
over the initial cost estimate." TRACE, which costs $49
million, is the third launch in the Small Explorer series of
small, quickly developed, relatively low-cost missions.

TRACE will be launched on an Orbital Sciences Corp.,
Dulles, VA, Pegasus-XL rocket released from an L-1011 jet
aircraft at the Western Range, Vandenberg Air Force Base, CA.
The launch window is open for 10 minutes.

TRACE will be the first space science mission with an open
data policy. All data obtained by TRACE will be available to
other scientists, students and the general public shortly after
the information becomes available to the primary science team.

The TRACE telescope was designed and developed in
cooperation between Lockheed Martin Corp. and Stanford
University. The spacecraft was designed and tested at Goddard,
which manages the mission for the Office of Space Science at
NASA Headquarters, Washington, DC.

Further information about the TRACE mission can be found on
the Internet at: